#74 Ketones, Fasting, and Flexibility: The Science of Optimizing Your Energy Systems for Endurance and Longevity with Dr Brianna Stubbs

In this episode of Ageless Athlete, we dive into the metabolic engine room with Dr. Brianna Stubbs—world-class endurance athlete and leading researcher at the Buck Institute for Research on Aging. Brianna bridges the worlds of elite performance and cutting-edge science, specializing in how ketones, fasting, and metabolic flexibility can shape our ability to recover, sustain energy, and age well.

This isn’t about dieting fads or silver bullets—it’s about understanding how your body fuels itself, and how those energy pathways evolve over time. Whether you’re an endurance athlete or someone simply trying to stay strong into your 40s, 50s, and beyond, Brianna’s insights will give you a fresh way to think about performance and longevity.

🧠 What You’ll Learn in This Episode:

• What metabolic flexibility actually is—and why it matters more as we age
• The role of exogenous ketones vs. endogenous ketones (and how they’re used differently)
• Why elite athletes may be “canaries in the coal mine” for aging
• How fasting can impact energy regulation, muscle retention, and cognitive performance
• Surprising myths and truths about the ketogenic diet
• What separates “TOPe’s” (Top Older Performers) from “NOPe’s” in the Buck Institute’s MOVE Study
• How Brianna personally trains, fuels, and recovers today—backed by both experience and data

🔬 References Mentioned:

• Buck Institute for Research on Aging: https://www.buckinstitute.org
• MOVE Study (Molecular Optimization Via Exercise): Recruiting older athletes for metabolic and molecular profiling
• Ketone Ester Research: Stubbs et al. (2017), Cell Metabolism – PMID: 28399454
• TOPe’s vs. NOPe’s framework: conceptual model comparing high-performing vs. low-performing older athletes
• HVMN Ketone Ester studies – Commercial application and early human performance trials

👤 About Dr. Brianna Stubbs:
Brianna is a former world champion rower for Team GB and currently serves as Director of Translational Science at the Buck Institute. She holds a PhD from Oxford in Metabolic Physiology and has spent the last decade studying how ketones and metabolic regulation affect performance and aging. She’s also competed in Ironman Kona and multi-day ultra-endurance events, making her both subject and scientist.

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